Rapid Plasma Reagin Test in Idaho

What this test measures

Syphilis is a bacterial infection passed through sexual contact. It can progress in stages and may cause few or no symptoms for long periods, which is why screening matters. The RPR test is a nontreponemal assay, meaning it detects antibodies released in response to infection rather than antibodies aimed at the bacterium itself. This makes it useful for screening and for tracking response to treatment.

The sample is a blood draw. Results are reported as reactive or nonreactive, and a reactive result is usually given as a titer, a measure of how diluted the sample can be while antibodies are still detected. Titers can rise during active infection and fall after successful treatment. A reactive screen is typically confirmed with a treponemal test such as a T. pallidum antibody assay.

The test may be ordered for routine sexual health screening, after a possible exposure, during pregnancy, or when symptoms suggest infection. Nontreponemal tests can occasionally be reactive for reasons unrelated to syphilis, and they can be negative very early in infection. Clinicians combine the RPR result with a confirmatory test, symptoms, and history before making decisions.